Most belt conveyors have a flexible endless belt comprising a load bearing body protected by top and bottom covers of a rubberlike material. The belt is supported at intervals by rollers. The belt is therefore supported against deflection as it curves about each roller, but flexes and sags between the rollers according to the variable load conditions. This flexing and sagging is most severe in the loading zone, because of the impact of the falling particulate material. The quasi-fluid characteristics of the material being loaded causes the material to flow laterally with considerable force upon impact against the belt.